Power shovels are in a category of excavation equipment used to remove large amounts of overburden and ore during a mining operation. One type of power shovel is known as a rope shovel. A rope shovel includes a boom, a dipper handle pivotally connected to a mid-point of the boom, and a shovel (also known as a dipper) pivotally connected at one end of the dipper handle. A cable extends over a pulley at a distal end of the boom and terminates at the end of the dipper handle supporting the shovel. The cable is reeled in or spooled out by electric, hydraulic, and/or mechanical motors to selectively raise and lower the shovel.
In most rope shovels, the shovel includes a door that is selectively swung open to dump material from the shovel into a waiting haul vehicle. The door is pivotally connected at one edge to a shovel body, and mechanically latched at an opposing edge. A cable (historically a rope and, hence, the term “rope shovel”) extends from an operator cabin over a boom-mounted pulley to the shovel latch. In this configuration, an operator can actuate the latch from inside a cabin of the shovel by tensioning the cable. When the shovel is held horizontally, tensioning the cable causes the latch to release the door and the door falls open under the force of gravity. When the shovel is held vertically, the door swings shut against the shovel body under the force of gravity, and the latch is biased to re-engage and hold the door in the closed position.
Although adequate for some applications, use of the cable to manually cause actuation of the dipper latch can be problematic in other applications. In particular, typical latches and associated cable linkages are under tremendous strain and cycle continuously. As a result, these components suffer high-cycle fatigue and must be serviced frequently to ensure that the latch operates effectively when manipulated by the operator via the cable. This frequent servicing results in machine downtime and lost productivity. Accordingly, an alternative source of power and control at the dipper latch is desired.
One attempt to improve durability of the dipper is disclosed in a technical article titled “ELECTRIC MINING SHOVEL PRODUCTIVITY ENHANCEMENTS: USING INNOVATION TO INCREASE MACHINE AVAILABILITY” that was written by Ronald J. Doll and published in 2009 (“the Doll paper”). In particular, the Doll paper describes a dipper having a new door that does not require a latch. Instead, the door includes an over-center link attached along a back side of the door, and a cam that selectively moves the link over-center during actuation. The cam is connected to a lever arm, which has a cable attached at one end. The cable is selectively tensioned by the operator to pivot the link, rotate the cam, and open the door when the door is in a position for gravity to pull it away from the dipper.
Although the dipper disclosed in the Doll paper may have improved durability because it no longer includes a latch, it may still be less than optimal. In particular, the door mechanism described in the Doll paper is still powered and/or controlled by the operator via a cable. This method of controlling and powering door actuation may still be prone to malfunctions.
The power shovel and dipper actuator of the present disclosure solve one or more of the problems set forth above.